Ajax components: provide a DummyAjaxRequestTarget instead of null if Ajax is not available, e.g. to onClick(AjaxRequestTarget)

It is a common pitfall not to think of AjaxRequestTarget maybe being null, e.g. in a Link's onClick method.
Even if the developer has this fact in mind, it is the same piece of code used to avoid NullPointerExceptions or other problems arising of it.

Wouldn't it be nice to have sort of a DummyAjaxRequestTarget? This could solve some common problems:

• NullPointerException due to the passed AjaxRequestTarget being null
• NullPointerExceptions due to AjaxRequestTarget#getPage() returning null
  there are probably more.

Also, it would be possible to throw more distinct Exceptions in cases where DummyAjaxRequestTarget cannot handle method calls.

I would love it, for better readibility and less runtime exceptions (even more as these runtime exceptions are only thrown under special conditions: js deactivated or similar)